The CAS Registry Mumber 54493-47-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,4,4,9 and 3 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 54493-47: (7*5)+(6*4)+(5*4)+(4*9)+(3*3)+(2*4)+(1*7)=139 139 % 10 = 9 So 54493-47-9 is a valid CAS Registry Number.